On the size of graphs without repeated cycle lengths (postprint)
In 1975, P. Erd {o}s proposed the problem of determining the maximum number $f(n)$ of edges in a graph with $n$ vertices in which any two cycles are of different lengths. In this paper, it is proved that $$f(n) geq n+ frac{107}{3}t+ frac{7}{3}$$ for $t=1260r+169 , (r geq 1)$ and $n geq frac{2119}{4}…